Thermal conductivity of near-stoichiometric (U, Er)O2 solid solutions

Thermal diffusivities of UO2 and UO2 doped with 1, 3, 5, 7 and 10 mol % ErO1.5 were measured in the range of 298-1673 K by a laser flash method and their thermal conductivities were calculated from the thermal diffusivity, the measured sample density and published specific heat capacity data. The temperature dependence of the thermal conductivity up to 1673 K in UO2 and UO2-doped with ErO1.5 was found to be modeled well using the phonon conduction equation, K = (A + BT)−1. The thermal conductivities of the UO2 and (U, Er)O2 solid solutions gradually decreased with the temperature. The thermal conductivity of the doped UO2 decreased relative to UO2 with an increase of ErO1.5 content at low temperatures, while it was independent of the ErO1.5 content at higher temperatures. The variation of parameters A and B as a function of ErO1.5 content is found experimentally and it is found that the dependence of the thermal conductivity of (U, Er)O2 on temperature up to 1673 K and on the ErO1.5 content can be expressed as K=KUO21+KUO2(kAy+kByT).